PARTICLE THEORY

• Density = Mass / Volume
• Volume = Mass / Density
• Mass = Density x Volume
• When a solid melts, the particles vibrate more.
• A liquid has no fixed shape or volume but always occupies the same space.
• During change of state, the mass of a substance remains the same.
• Gases have no fixed shape or volume and can be compressed into smaller spaces.
• The density of a gas is very low because its particles are far apart.
• Increasing temperature increases the kinetic energy of particles which causes them to move faster.
• Gases have no definite shape or volume.
• Solid to liquid - melting.
• Liquid to solid - freezing.
• Gas to liquid - condensation.
• Solid to gas - sublimation.
• Gas to solid - deposition.
• Liquid to gas - evaporation.
• Impurities raises the boiling point, but decreases the melting point.
• Diffusion is the movement of particles from a region of high concentration to one of low concentration.
• Helium is less dense than air, therefore, helium - filed balloons raise when released in the air.
• Particles of Helium are smaller than those of gases in air, therefore, balloons inflated with Helium deflates faster rather than one filled with air.